The first session of this semester’s Race to the Wall took place today, in which teams from DT066 attempted the task. Teams from DT009 will attempt the task for the first time this Friday (10:00-16:00). Their results will be interleaved with those shown below.

Teams from DT066 who have not already recorded a time are welcome to attempt the task this Friday or during next Wednesday’s class. However, because DT066 teams who complete the challenge any time after today are doing so late, they must be ranked below all the teams who validated for size and weight and recorded a time today. Please note that this does not apply to DT009 teams who complete the challenge on Friday, since that will be their first opportunity.

The current ranking stands as follows:

Ranking

Team

Mass

Size

Time [s]

1

Zelda

Y

Y

4.502

2

Out of the Box

Y

Y

5.069

3

HAL

Y

Y

5.697

4

Ninja Turtles

Y

Y

7.403

5

Kratos

Y

Y

7.527

6

Manhattan Project

Y

Y

12.451

7

TED (The Extreme Danger)

Y

Y

15.397

8

TNT

Y

Y

20+

9

Liz

Y

Y

20+

10

ComBot

Y

Y

20+

Well done to all the teams who completed the challenge today!

Laser Cutting

Teams who wish to get parts laser cut for their robot can still send me drawings and I’ll do my best to facilitate them. However, I’m not sure exactly when I’ll have access to the laser cutting machine and when I won’t, so please don’t send drawings at the very last minute and expect them to be cut immediately.

File format for laser cutting

If you’re drawing your pieces in AutoCAD, the easiest file format for me to work with is DXF.

If you’re drawing your pieces in Inkscape, the easiest file format for me to work with is the native SVG file format.

Please send me a single file (either SVG or DXF) containing all of the parts you want cut. Please don’t send a separate file containing each part, because that makes it very labour intensive for me.

Your drawing should contain only very thin black lines. There should be no filled shapes – just thin lines on a blank background. The laser simply cuts every line in the drawing.

Do not include dimension labels or other markings that you don’t want cut out because the laser will cut out these shapes also.

We are not offering you the option of engraving at this point because it takes a long time on the machine and makes the process more inconvenient for me.

The individual pieces in your drawing should be closely packed so that a minimal amount of material is wasted in between parts. I’m including an image of my drawing below to explain what I mean.

Laser cutter schematic for my Race to the Wall robot. Note that only cut lines are included in the diagram and all pieces are tightly packed together to save material. Although your pieces will be packed together like this before cutting, when you submit your drawing it’s better to leave some space between the parts so that I can move them around to fit the available space on the sheet I’m cutting.

Your pieces will be cut from 3mm thick acrylic sheet. The sheets we have in stock all seem to be clear coloured, so keep in mind that the laser at the finish line of the Race to the Wall may pass through it.

If you’re the person who has been given the job of drawing the laser cutting plans for your team’s robot, please ask your teammates to review the drawings with you before you get them cut out. Extra pairs of eyes make it easier to spot errors or oversights in advance.

Another great way to verify that your pieces will fit together the way you expect is to print them out at their actual size on a normal sheet of A4 paper, then stick it down on an A4 piece of 3mm foam board. If you then cut it out very carefully using a craft knife and a metal ruler, you can produce an excellent working replica of each piece. Cutting out curves is tricky, but straight lines can be cut very accurately with care, which allows you to test interlocking pieces. This is exactly what I do myself when I’m planning a design at home.

Depending on the design of your robot, you may even find that your foam board prototype is good enough to complete the Race to the Wall!

If you need to laser cut gears for your robot, Inkscape has a really great tool for drawing them. Go to “Extensions menu -> Render -> Gear…”. There are a couple of good tutorials on YouTube for using this gear tool.

If you want to make very precisely fitting parts, remember that the kerf (the width of the laser cut) is approximately 0.1mm. Roughly speaking, this means that the laser removes material 0.05mm either side of the line it follows. For most purposes, you don’t really need to worry about this, but in some instances it can be significant.

5 Responses to Race to the Wall – interim ranking and chances to try again

Reblogged this on Out of the Box. . ! and commented:
Here we are , we got second in this race.
I’ll send some photos and video on progreission of building the robot and the problems we had.
It was realy intersting, looking forward to the final tourtment.